The article "Biomolecular condensates with complex architectures via controlled nucleation" by Erkamp et al. (2024) introduces a method to create custom multiphase architectures in biomolecular condensates by nucleating new droplets within existing condensates. This process occurs due to limited diffusion in dense condensates and composition changes induced by altering experimental conditions. The designed architectures are transient states that can be created out of equilibrium. The authors provide a detailed method for understanding and designing a range of condensate architectures, which will enable researchers to incorporate sophisticated compartmentalization and functionality in condensates for various applications, including biotechnology, artificial cells, and origin-of-life research. The study explores how to design condensates with different mesoscale architectures, focusing on the number and location of droplets of each phase. By forcing a change in the composition of the condensates, they induce the nucleation of chosen droplets, creating complex architectures in a multiphase condensate model. The architecture of the condensate is determined by how the temperature is reached, not just the temperature itself. Rapid cooling causes the formation of higher-energy transient architectures, which can be reversible and long-lived due to slow diffusion. The authors use a model complex coacervate system to demonstrate their method. They show that by changing the experimental conditions, such as temperature and ionic strength, they can control the nucleation of droplets and the resulting architecture. This method allows for the prediction and design of complex architectures, which can be used to control the uptake rate of cargo molecules in drug-delivery systems. Overall, the article presents a general strategy for creating complex structured condensates out of equilibrium, providing insights into the structure of condensates in cells and their dynamic behavior.The article "Biomolecular condensates with complex architectures via controlled nucleation" by Erkamp et al. (2024) introduces a method to create custom multiphase architectures in biomolecular condensates by nucleating new droplets within existing condensates. This process occurs due to limited diffusion in dense condensates and composition changes induced by altering experimental conditions. The designed architectures are transient states that can be created out of equilibrium. The authors provide a detailed method for understanding and designing a range of condensate architectures, which will enable researchers to incorporate sophisticated compartmentalization and functionality in condensates for various applications, including biotechnology, artificial cells, and origin-of-life research. The study explores how to design condensates with different mesoscale architectures, focusing on the number and location of droplets of each phase. By forcing a change in the composition of the condensates, they induce the nucleation of chosen droplets, creating complex architectures in a multiphase condensate model. The architecture of the condensate is determined by how the temperature is reached, not just the temperature itself. Rapid cooling causes the formation of higher-energy transient architectures, which can be reversible and long-lived due to slow diffusion. The authors use a model complex coacervate system to demonstrate their method. They show that by changing the experimental conditions, such as temperature and ionic strength, they can control the nucleation of droplets and the resulting architecture. This method allows for the prediction and design of complex architectures, which can be used to control the uptake rate of cargo molecules in drug-delivery systems. Overall, the article presents a general strategy for creating complex structured condensates out of equilibrium, providing insights into the structure of condensates in cells and their dynamic behavior.